Trench shoring apparatus

ABSTRACT

A trench shoring apparatus braces the substantially vertical walls of an earthen excavation. Telescoping wall support legs permit the apparatus to be easily adjusted for use in trenches of various depths. Horizontal wall support arms joined to the wall support legs retain and stabilize trench wall soils and provide a mechanism for mounting additional soil retaining components. Flexible anchor support arms transfer the load produced by the shifting trench walls to a location remote from the trench. The trench shoring apparatus, additionally, may be partially folded and disassembled for ease in transportation and storage.

FIELD OF THE INVENTION

The present invention relates to the shoring, bracing, and cave-inprevention of earthen trenches. In particular, it relates to a novel andimproved trench shoring apparatus that is portable, lightweight,adjustable in height, and adjustable to the terrain immediatelysurrounding a given trench excavation.

BACKGROUND OF THE INVENTION

Throughout the United States innumerable earthen trenches are excavatedannually. Such trenches are employed in the construction of engineeringstructures ranging from building foundations to sewer lines. Thelaborers assembling such structures are often required to work withinthese trenches. Often they are fatally injured while doing so.

While trenches may be excavated to a depth greater than a man's height,they seldom penetrate the relatively unconsolidated soils or sedimentsthat overlay solid bedrock below. This unconsolidated matter is usuallya mixture of decaying vegetative material and fine-grained wind or waterborne minerals. When exposed by an excavation such as a trench, thesematerials have proven to be extremely unstable and prone to cave-inunder the slightest load. Thus, the possibility of an excavation'scollapse is always substantial. Indeed, it has been estimated that twohundred fatalities caused by trench cave-ins occur within the UnitedStates each year.

Construction companies are notoriously lax in obeying regulationspromulgated by government agencies. Regulations of the OccupationalHealth and Safety Administration (OSHA), for instance, mandate thattrenches or excavations of a depth greater than an established minimummust be sloped or shored. As the sloping of excavations is a timeconsuming process requiring the movement of earthen material beyond thatabsolutely necessary for construction purposes, it is avoided whenpossible to reduce expenditures. Additionally, the trench boxescurrently available for shoring trenches are time consuming to erect atconstruction sites due to their large size, weight, and complexity.Beyond this, trench box cross braces restrict and impede free movementwithin the trench as well as the rate at which work can be performed.Since construction companies usually establish goals of performingassignments as rapidly as possible, neither trench shoring nor slopingoperations are performed without great hesitation and reluctance. Aslong as this remains the case, the risk to human life at constructionsites will remain unnecessarily high.

The need has arisen for an apparatus which will prevent the cave-in ofan earthen trench and may be erected rapidly at the construction site.

DESCRIPTION OF THE RELATED ART

In the past, devices have been developed to prevent the collapse ofearthen trench walls. One such device utilizes two panels positionedopposite one another against the two walls of a trench. Cross membersspanning the distance between such panels bear the forces transmittedfrom earthen wall and provide for its support. This "trench box"apparatus has become well known in the art. An example of such a deviceis contained in U.S. Pat. No. 4,993,880 to John Collins granted Feb. 19,1991. This device's great weight and bulk make it difficult to transportand time consuming to install. These drawbacks frequently prevent itsuse when worker safety would otherwise demand it.

A second type of device for shoring trenches is illustrated in U.S. Pat.No. 991,981, granted May 9, 1911, to Albert H. Harvard. Harvard's patentdiscloses a grave brace that transmits the load produced by shiftingtrench wall sediments to staked members located outside the trench andupon the ground's surface. While an improvement, in terms ofportability, over the trench box, Harvard's device is only capable ofshoring a very shallow trench, and transmits no portion of the trenchwall load to the trench floor.

None of the above inventions and patents, taken either singly or incombination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION

By the present invention, an improved trench shoring apparatus for usein supporting the walls of an excavated earthen trench.

Accordingly, it is a principal object of this invention to provide atrench shoring apparatus such that its horizontal load bearing membersmay be placed upon the ground's surface outside of the trench allowingunimpeded movement therein.

It is a secondary object of this invention to provide a trench shoringapparatus such that its wall supporting legs span the trench's heightand firmly insert into the trench floor.

It is another object of this invention to so construct a trench shoringapparatus wherein its height may be adjusted to accommodate trenches ofvarious depths.

Still another object of the present invention is to provide a trenchshoring apparatus that may be readily adapted to terrain of varyingrelief surrounding a given trench excavation.

It is a further object of the present invention to construct a trenchshoring apparatus of lightweight components which can be easilydisassembled and moved.

It is an additional object of this invention to provide a trench shoringapparatus of compact size for ready storage when not in use.

It is the object of this invention to provide improved elements andarrangements thereof in a trench shoring apparatus for the purposesdescribed which is inexpensive, dependable and fully effective inaccomplishing its intended purposes.

These and other objects of the present invention will become readilyapparent upon further review of the following specification an drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective and environmental view of a trench shoringapparatus within a trench.

FIG. 2 is a side elevational and environmental view of a trench shoringapparatus within a trench.

FIG. 3 is front elevational and cross sectional view of a trench shoringapparatus.

FIG. 4 is a rear elevational and detail view of a trench shoringapparatus showing pivoting horizontal support arms.

FIG. 5 is a side elevational, cross sectional, and detail view of ananchor member and flexible strap stored therein.

FIG. 6 is a side elevational and detail view of an alternativeembodiment of a trench shoring apparatus with an anchor member having achain.

FIG. 7 is a side elevational and detail view of an alternativeembodiment of a trench shoring apparatus with an anchor member having acable.

FIG. 8 is a side elevational and detail view of an alternativeembodiment of a trench shoring apparatus with an anchor member having astrap.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, there is shown in FIG. 1 a trench shoringapparatus 1 for use by persons in the construction industry or the like,such apparatus being temporarily secured against an earthen trench wall2. The shoring apparatus 1 has several primary load bearing members.Vertical wall support legs 3, 3' extend from the trench floor 4 to theground surface 5 above. The vertical wall support legs 3, 3' are heldfirmly against the trench wall 2 by hollow anchor members 6, 6'. Loadsgenerated by shifting trench soils exerted upon support legs 3, 3' aretransmitted to the ground surface 5 through the anchor members 6, 6'.Hollow anchor members 6, 6' are of a length sufficient to reach beyondthe slump zone of the earthen material to be shored. The width of thisslump zone has been defined in the soil mechanics art as a function ofthe earthen material's angle of repose and excavation depth.Additionally, anchor members 6, 6' support the trench wall 2 withsufficient strength to provide the required margin of safety for thoseentering the trench. Finally, attached to vertical wall support legs 3,3' are horizontal support arms 7, 7'. The support arms 7, 7' provideadditional support to the trench wall 2 and provide a U-shaped seatwherein wall support members 8 may be joined to vertical wall supportlegs 3, 3'.

The trench shoring apparatus 1 may be firmly affixed to the earth.Anchoring daggers 9 are joined to the ends of vertical wall support legs3, 3'. The V-shaped daggers 9 may be inserted into the trench floor 4preventing horizontal movement of the support legs 3, 3' when underloads from shifting trench wall soils. On the other hand, stakes 10,attached to the ends of anchor members 6, 6', are provided with similarV-shaped cross sections and are capable of being driven into the groundsurface 5.

In order to secure an optimal fit of the trench shoring apparatus 1within a trench, minimize shipping difficulties, and reduce the volumefor storage, several of the apparatus' components telescope within eachother. Vertical support legs 3, 3' are each constructed of three nestedand telescoping tubes 11, 12, and 13. In the preferred embodiment, tubes11, 12, and 13 have a square cross section. When the vertical supportlegs 3, 3' are reduced to a minimum, tube 11, having the largest crosssectional area, houses both tubes 12 and 13 having progressively smallercross sectional areas. Similarly, tube 12, which is slightly larger thantube 13, houses tube 13 when the length of either vertical support leg3, 3' is reduced. Two series of linearly arranged and opposing holes 14seen in FIGS. 1 and 2 run the length of tubes 11, 12, and 13 permitremovable pins 15 to join tubes 11, 12, and 13. Pins 15 may be removedas desired allowing the length of vertical support legs 3, 3' to beadjusted to fit the exact height of a trench wall 2. In the preferredembodiment, vertical support legs 3, 3' may be telescoped toapproximately three times the retracted legs' length. With the tubes 11,12, and 13 retracted, the apparatus 1 may be most easily stored andtransported.

Hollow anchor members 6, 6' are each constructed of two nested andtelescoping tubes 16, 17. In the preferred embodiment, the tubes 16 and17 have a square cross section. Tube 16, having dimensions larger thanthose of tube 17, houses the latter when the length of anchor members 6,6' are reduced to a minimum for storage purposes. A hole piercing tubes16, 17 permits a removable pin 19 to join tubes 16, 17 when insertedtherein. With tubes 16, 17 joined by pin 19, the trench shoringapparatus 1 may be employed in normal trench shoring operations.

Several of the preferred embodiment's components pivot upon each otherin order to enhance its ability to be transported from one constructionsite to another or to reduce its volume for storage. First, V-shapeddaggers 9 are pivotly joined to the ends of vertical support legs 3, 3'.The daggers 9 may pivot on pins 20 inserted through daggers 9 andtelescoping tubes 13. The apparatus is constructed such that eachdagger's pointed tip 21 may only pivot away from the trench wall 3 whenemployed in trench shoring operations. In this manner, a horizontalforce exerted upon the support legs 3, 3' by the slumping or shiftingtrench wall 2 will lock the daggers 9 and support legs 3, 3' in avertical position. Additionally, V-shaped stakes 10 are pivotly joinedto the ends of anchor members 6, 6'. The stakes 10 may pivot on pinsinserted through each of stakes 10 and telescoping tubes 17. The trenchshoring apparatus 1 is constructed such that each stake's pointed tip 22may pivot only toward the trench wall 3 when employed in trench shoringoperations. In this manner, a horizontal force exerted upon the supportlegs 3, 3' will lock stakes 10 in a position substantially perpendicularto anchor members 6, 6'. Finally, as may be seen in FIG. 4, horizontalsupport arms 7, 7' may pivot vertically upon bolts 43 threaded into nuts44 joined to vertical support legs 3, 3'. Joined to the support arms 7,7' are reinforcing flanges 24, 24'. Reinforcing flanges 24, 24' areconstructed such that the flange 24 pivots on a smaller radius thanflange 24'. Thus, when fully pivoted against tube 11, flanges 24 and 24'do not contact each other.

It has been recognized that the ground surface 5 and trench wall 2 areseldom exactly perpendicular to each other. For this reason, anchormembers 6, 6' are pivotly attached to vertical support legs 3, 3' bypins 45. Pins 45 permit anchor members 6, 6' to lay upon the groundsurface 5, provided that such surface is relatively flat, regardless ofthe angle formed between the trench wall 2 and the surface 5.

As the ground surface 5 adjacent to a trench wall 2 is sometimesundulating, anchor members 6, 6' are constructed such that tubes 16 and17 may be connected by a flexible fabric strap 23 rather than pin 19.The flexible strap 23 permits anchor members 6, 6' to hinge and conformto irregular terrain adjacent to the trench wall 2. FIG. 1 shows theanchor member 6 in the usual operative mode upon a substantially planarground surface with tubes 16 and 17 connected by pin 19. Also shown inFIG. 1 is anchor member 6' wherein tubes 16 and 17 are joined by a strap23. The strap 23 permits anchor member 6' to extend over an earthen berm25 adjacent to the trench wall 2 allowing stake 10 to be inserted intoconsolidated soil beyond. The exposed length of the strap 23 may beadjusted, as shown in FIG. 5, by inserting a removable pin 26 into oneof the retaining loops 27 sewn into the strap 23.

It has been contemplated that anchor members having alternate forms ofconstruction yet having the equivalent strength and weight of anchormembers 6, 6' may be employed in the subject apparatus 1. A chain, acable, or a strap, among others, may be employed as effectivesubstitutes for anchor members 6, 6'. FIG. 6 shows a chain 28 employedas an anchor member. FIGS. 7 and 8 respectively show a cable 29 and astrap 30 employed as substitutes for anchor members 6, 6'.

Referring back to FIG. 1, the preferred embodiment of the trench shoringapparatus 1 is shown with two vertical support legs 3, 3' laterallyspaced upon trench wall 2. When in use at other construction sites orthe like, any number of similar vertical support legs may be employed asrequired. These additional support legs would be equivalently spacedalong a trench wall and may be connected to each other with lateral wallsupport members 8. Lateral wall support plates 31 may also be added.

Maximum support for the trench wall 2 is provided when lateral wallsupport members 8 are placed within opposing horizontal support arms 7,7'. The U-shaped support arms 7, 7' cradle and retain the lateral wallsupport members 8. Between the lateral wall support members 8 and thetrench wall is placed a lateral wall support plate 31. The plate 31retains earthen material within the trench wall 2. It is contemplatedthat the support plate 31 may be constructed from a variety ofmaterials: wood, iron, aluminum, etc., and in a variety ofconfigurations such that the entire trench wall 2 or a fraction thereofmay be supported by the plate 31. When it is desired that support plate31 be suspended above the trench floor 4 as seen in FIG. 1, fastenersmay be employed to join plate 31 to horizontal support arms 7, 7'.

It is to be understood that the present invention is not limited to thesole embodiment described above, but encompasses any and all embodimentswithin the scope of the following claims.

I claim:
 1. A trench shoring apparatus for use in the shoring, bracing,and cave-in prevention of earthen trenches comprising:a vertical wallsupport leg, adapted to extend substantially vertically from a trench'sfloor to the ground's surface above; a plurality of horizontal supportarms joined to said support leg and adapted to receive lateral wallsupport members, said horizontal support arms being pivotally joined tosaid support leg; and, an anchor means joined to said support leg,whereby loads generated by shifting trench wall soils exerted upon saidsupport legs are transmitted to the ground's surface through said anchormeans and said arms may be rotated into a position substantiallyparallel to said support leg to reduce the width of said trenchanchoring apparatus permitting easy storage thereof when not in use. 2.The trench shoring apparatus of claim 1 wherein said vertical wallsupport leg includes:a plurality of nested support members, whereby saidsupport members may be moved relative to one another and telescoped topermit use of said trench shoring apparatus in trenches of varyingdepths.
 3. The trench shoring apparatus of claim 1 wherein said verticalsupport leg includes:an anchor dagger, said dagger joined to the bottomof said support leg, whereby said dagger may be inserted into the trenchfloor preventing horizontal movement of said support leg when under loadfrom shifting trench wall soils.
 4. The trench shoring apparatus ofclaim 3 wherein said anchoring dagger is pivotally joined to the bottomof said support leg. whereby said dagger may be rotated into a positionsubstantially parallel to said support leg reducing the length of saidtrench shoring apparatus permitting easy storage thereof when not inuse.
 5. The trench shoring apparatus of claim 1 wherein said anchormeans includes:a plurality of hollow anchor members; a flexibleconnecting means joining said anchor members, whereby said flexibleconnecting means allows said anchor members to hinge and conform toirregular terrain adjacent to a trench excavation; and, a stake joinedto one of said hollow anchor members, said stake adapted to penetratethe earth.
 6. The trench shoring apparatus of claim 5 wherein saidplurality of hollow anchor members nest within one another and areadapted to be telescopically extended or retracted, whereby the lengthof said anchor means may be reduced permitting easy storage thereof whennot in use.
 7. The trench shoring apparatus of claim 5 wherein saidflexible connecting means comprises:a flexible strap.
 8. The trenchshoring apparatus of claim 5 wherein said stake is pivotally joined toone of said hollow anchor members, whereby said stake may be rotatedinto a position substantially parallel to said adjoining hollow anchormembers permitting easy storage thereof when not in use.
 9. The trenchshoring apparatus of claim 1 wherein said anchor means comprises oneof:a linked chain, a cable, and fabric strap.
 10. A trench shoringapparatus for use in shoring, bracing, and cave-in prevention of earthentrenches comprising:a plurality of vertical wall support legs, said legsadapted to extend substantially vertically from a trench's floor to theground's surface above; a means for anchoring each of said wall supportlegs, whereby loads generated by shifting trench wall soils exerted uponeach of said support legs are transmitted to the ground's surfacethrough said anchoring means; a plurality of horizontal support armsjoined to each said support leg, said horizontal support arms beingpivotally joined to each of said support legs; a plurality of lateralwall support members removably joined to said support arms, whereby eachof said support members extends horizontally along the trench wall andconnects two of said vertical support legs adjacently positioned againstthe trench wall; and, a plurality of lateral wall support plates, saidplates positioned between the trench wall and said lateral wall supportmembers, whereby each of said support plates provides additional supportfor the trench wall and said arms may be rotated into a positionsubstantially parallel to each said support leg joined thereto to reducethe width of said trench anchoring apparatus permitting easy storagewhen not in use.
 11. The trench shoring apparatus of claim 10 whereineach of said vertical wall support legs include:a plurality of nestedsupport members, whereby said support members may be moved relative toone another and telescoped to permit use of said trench shoringapparatus in trenches of varying depths.
 12. The trench shoringapparatus of claim 10 wherein each of said vertical support legsinclude:an anchoring dagger, said dagger joined to the bottom of eachsaid support leg, whereby said dagger may be inserted into the trenchfloor preventing horizontal movement of each said support leg when underload from shifting trench wall soils.
 13. The trench shoring apparatusof claim 12 wherein said anchoring dagger is pivotally joined to thebottom of each said support leg, whereby each said dagger may be rotatedinto a position substantially parallel to said support leg reducing thelength of said trench shoring apparatus permitting easy storage when notin use.
 14. The trench shoring apparatus of claim 10 wherein said anchormeans includes:a plurality of hollow anchor members; a flexibleconnecting means joining said anchor members, whereby said flexibleconnecting means allows said anchoring means to hinge and conform toirregular terrain adjacent to a trench excavation; and, a stake joinedto one of said hollow anchor members, said stake adapted to penetratethe earth.
 15. The trench shoring apparatus of claim 14 wherein saidplurality of hollow anchor members nest within one another and areadapted to be telescopically retracted, whereby the size of said trenchshoring apparatus may be reduced allowing easy storage thereof when notin use.
 16. The trench shoring apparatus of claim 14 wherein saidflexible connecting means comprises:a flexible strap.
 17. The trenchshoring apparatus of claim 14 wherein said stake is pivotally joined toone of said hollow anchor members, whereby said stake may be rotatedinto a position substantially parallel to said adjoining hollow anchormembers permitting easy storage when not in use.
 18. The trench shoringapparatus of claim 10 wherein said anchor means comprises one of:alinked chain, a cable, and a fabric strap.